Microsoft released the December 2019 2019 non-security Microsoft Office updates that fix issues and add stability and performance improvements to Windows Installer editions of Office 2016. The updates only apply to Outlook and Skype for Business 2016, while the third addresses issues present in Standard, Professional Plus, Professional, Home and Student editions. None of the updates released today apply to the Click-to-Run Office apps such as Microsoft Office 365 Home and Business apps. The list of updates issued today and the updates issued are available below.
Source: https://www.bleepingcomputer.com/news/security/microsoft-releases-december-2019-office-updates-with-auth-issue-fix/